import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory
import os

import launch_ros.parameter_descriptions

def generate_launch_description():

    #获取默认的URDF路径
    urdf_package_path = get_package_share_directory('fishbot_description')
    default_urdf_path = os.path.join(urdf_package_path,'urdf','frist_robot.urdf')
    default_rivz_config_path = os.path.join(urdf_package_path,'config','dispaly_robot_model.rviz') 

    #声明urdf目录的参数，方便修改
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name='model',default_value=str(default_urdf_path),description='加载模型文件路径'
    )

    #通过文件路径获取内容并转化为参数值对象，以供传入 robot_state_publisher
    substiutions_command_rseult = launch.substitutions.Command(['xacro ',launch.substitutions.LaunchConfiguration('model')])
    robot_description_value = launch_ros.parameter_descriptions.ParameterValue(substiutions_command_rseult,value_type=str)

    #节点启动
    action_robot_state_publisher = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description_value}]
    )

    #节点启动
    action_joint_state_publisher = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher'
    )

    action_rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d',default_rivz_config_path]
    )

    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_state_publisher,
        action_joint_state_publisher,
        action_rviz_node
    ])